TGIF prostate cancer news: Friday, October 3

The important news today appears to be clear confirmation that a high- (or low-) fiber diet won’t affect your risk for prostate cancer (at least, not over an 8-year timeframe). In other news today:

  • Prostate weight may impact risk for recurrence following surgery
  • Just over 25 percent of patients receiving hormone therapy will be diagnosed with a psychiatric disorder within the following 7 or so years
  • The relative values of two ways to assess erectile function have been investigated

Based on data collected as part of the European Prospective Investigation into Cancer and Nutrition (EPIC) study, which has enrolled more than 142, 000 men, Suzuki et al. have reported that over an average 8.7 years follow-up, prostate cancer was diagnosed in 2,747 men. There was no overall association noted between dietary fiber intake (total, cereal, fruit or vegetable fiber) and prostate cancer risk, although calibrated intakes of total fiber and fruit fiber were associated with nonstatistically significant reductions in risk. There was no association between fiber derived from cereals or vegetables and risk and no evidence for heterogeneity in any of the risk estimates by stage or grade of disease. Suzuki et al. state unequivocally that “Our results suggest that dietary fiber intake is not associated with prostate cancer risk.”

Chu et al. have prospectively studied the impact of prostate weight on risk for positive surgical margins in 1,500 patinets who underwent laparoscopic radical prostatectomy (LRP, 399 cases)  or robot-assisted laparoscopic prostatectomy (RALP, 1,101 cases) between December 2000 and June 2006 at City of Hope National Medical Center. They found that of the 1,500 patients, 345 (23 percent) had one or more positive margins. Patients with low median prostate weight (49 g) had a significantly higher positive margin rate (p < 0.0001) and incidence of extraprostatic extension by tumor (p = 0.04), and were 1.523 times more likely to have positive margins. They conclude that low prostate weight may be a determinant of a higher recurrence rate and more aggressive disease. The “New” Prostate Cancer InfoLink continues to be concerned by the rates of positive surgical margins reported in modern LRP/RALP studies. The data reported by Chu et al. here are comparable to those reported by Shikanov et al. in a prior study. However, a report by Touijer et al. from Memorial Sloan-Kettering Cancer Center suggests that rates of 11 percent are achievable.

Diblasio et al. have investigated the prevalence of de novo (newly evident) psychiatric illness following initial ADT treatment for prostate cancer, and the predictive factors associated with risk for psychiatric illness in this patient population. Theith study was a retrospective, single-institution analysis of patients started on ADT between 1989 and 2005, and it excluded men receiving only neoadjuvant ADT. The authors divided the patients into three groups for analysis: those who had pre-ADT psychiatric illness; those with de novo psychiatric illness, and those who had no psychiatric illness. Their database include 395 patients with a mean age of 71.7 years at ADT initiation. Thirty-four men (8.6 percent) had pre-ADT psychiatric illness. At mean follow-up of > 7 years, 101 men (27.9 percent) had been diagnosed with de novo psychiatric illness. The most common diagnoses were depression (n = 57), dementia (n = 14), and anxiety (n = 9). On multivariate analysis, an increasing PSA prior to ADT treatment was predictive of post-ADT anxiety. The authors conclude that while no predictive factors were identified for de novo psychiatric illness, increasing PSA was associated with de novo anxiety, while recognizing that the relationship between de novo psychiatric illness and ADT therapy should be investigated in a prospective clinical trial.

Schroek et al. have attempted to compare the relative values of the 5-item short version of the International Index of Erectile Function (IIEF-5) and the Expanded Prostate Cancer Index Composite (EPIC) as tools to assess erectile function. Patients with prostate cancer had to complete the IIEF-5 and the EPIC within 7 days of each other to be eligible. Based on an analysis of 102 questionnaire pairs, EPIC sexual domain scores ≥ 60 had high concordance with IIEF-5 scores ≥ (98 percent) and with nearly all single-item definitions of potency (≥ 71percent). The EPIC sexual domain score ≥ 80 is a very strict definition of potency, and only 54 percent of patients with IIEF-5 scores ≥ 22 met this threshold. The authors determined that an IIEF-5 score ≥ 20 was “the ideal cutoff” for defining potency and corresponded with an EPIC sexual domain score ≥ 60. Apparently, potency rates varied widely, depending on the definition of potency. While the current results may help with the interpretation of sexual function outcomes data in patients with prostate cancer, The “New” Prostate Cancer InfoLink suspect that we need to establish better and more age-appropriate definitions of potency in order to more accurately assess the effects of treatment (on erectile function and for erectile dysfunction) on potency.

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